Utility Systems; Heating System Operation; Heating System Troubleshooting; Heating System Removal, Repair And Installation - Cessna 177 SERIES Service Manual

SECTION 14
UTILITY SYSTEMS
Page No.
TABLE OF CONTENTS Aerofiche/Manual
UTILITY SYSTEMS .........
1. L9/14-1
Trouble Shooting ....... 1L14/14-6
Heating Systems ..... .... 1L9/14-1
Removal, Repair and
Description .1...... . 1L9/14-1
Installation ........ 1L14/14-6
Operation .......... 1L9/14-1
Ventilation Systems . .......
1L14/14-6
Trouble Shooting ...
. 1L9/14-1 Description
.... 1L14/14-6
Removal, Repair and
Operation .. . . .. . 1L14/14-6
Installation
... .... 1L9/14-1
Trouble Shooting ....... 1L14/14-6
Defroster Systems ........ 1L14/14-6
Removal, Repair and
Description . ... . . 1L14/14-6
Installation .......
1L14/14-6
Operation . . . . . . .L14/14-6
14-1. UTILITY SYSTEMS.
controls. damaged air ducting. or defects in the ex-
-haust muffler. In most cases, valves or controls can
14-2. HEATING SYSTEM.
be freed by proper lubrication. Damaged or broken
parts must be repaired or replaced. When checking
14-3.
DESCRIPTION.
The heating system is corn-
controls, ensure valves respond freely to control
prised of the heat exchange section of the exhaust
movement, that they move in the correct direction
muffler, a mixing airbox with shut-off valve on the
and that they move through their full range of travel
forward side of the firewall, a push-pull control on
and seal properly. Check that hose are properly se-
the instrument panel, outlets and flexible ducting
cured and replace hose that are burned, frayed. or
connecting the system.
crushed. If fumes are detected in the cabin, a thor-
ough inspection of the exhaust system should be ac-
14-4. OPERATION.
Ram air is ducted through an complished.
Refer to applicable paragraph in Section
engine baffle inlet and heat exchange section of the 11 for this inspection.
Since any holes or cracks
exhaust muffler, to a mixing airbox on the forward
may permit exhaust fumes to enter the cabin, re-
side of the firewall. Unheated ram air, routed
placement of defective parts is imperative because
through a duct connected to a vertical engine baffle, fumes constitute an extreme danger.
Seal any gaps
is also ducted to this airbox.
The airbox valve pro-
in heater ducts across the firewall with Pro-Seal
vides an operation in which the first one inch of
700 (Coast Pro-Seal Co., Chemical Division, Los
travel of the "CABIN AIR/HEAT" control results in
Angeles, California) compound or equivalent com-
varying degrees of fresh air flow. A detent is pro- pound.
vided on the mixing valve at the full unheated fresh
air position. As the control is pulled out past the de- 14-6. REMOVAL, REPAIR AND INSTALLATION.
tent position, further extension of the control results
Figure 14-1 illustrates the heating and defrosting
in mixing of increased quantities of heated air. Pull-
systems and may be used as a guide during removal,
ing the control full out provides maximum flow and
installation and repair of heating system components.
heated air. From the mixing airbox, air flows into a
Burned, frayed or crushed hose should be replaced
duct across the aft side of the firewall where it is dis-
with new hose, cut to length and installed in the orig-
tributed into the cabin. inal routing.
Trim hose winding shorter than the
hose to allow clamps to be fitted. Defective air valves
14-5. TROUBLE SHOOTING.
Most of the opera-
must be repaired or replaced. Check for proper op-
tional troubles in the heating and defrosting systems
eration of valves and their controls after repair or
are caused by sticking or binding valves or their replacement.
Change 7 14-1